Pin and clevis type shackles which include a lock for preventing unwanted disengagement of the pin from the clevis are disclosed by the following U.S. Pat. Nos. 2,097,465, granted Nov. 2, 1937, to William D. Morrison; 3,754,418, granted Aug. 28, 1973, to Peter B. Miller; and 4,423,610, granted Jan. 3, 1984, to Judy L. Hart and William A. Munday. The latter patent discusses how a closure pin that is merely screw connected to the clevis can become disconnected from the clevis when subjected to vibration and other forces imposed upon it when in use. A principal object of the present invention is to provide an improved shackle clevis and pin shackle having a pin lock mechanism which is a part of the pin and the clevis, so as to add no additional separable part to the shackle mechanism.